Fluid pressure transmission system



Maly 18,"1954 J. v. cowAN FLUID PRESSURE TRANSMISSION SYSTEM Filed Dec.4, 1952 2 Sheets-Sheet 1 JOHN V. COWAN ATTORNEY May 18 ,1954 J. v. COWANFLUID PRESSURE TRANSMISSION SYSTEM Filed Dec. 4, 1952 2 Sheets-Sheet 2IN VEN TOR JOHN V COWAN MEM ATTORNEY Patented May 18, 1954 FLUIDPRESSURE TRANSMISSION SYSTEM John V. Cowan, Danbury, Conn., assignor toSperry Products, Inc., Danbury, Conn., a corporation of New YorkApplication December 4, 1952, Serial No. 324,093

claims. l

This invention relates to liquid control gear of the type whereinmovement of a member at a transmitting station is caused to controlmovement of a member at a receiving station. More particularly thisinvention relates to control gear of this type wherein the transmittingand receiving stations are connected by a liquid transmission system.One such system is shown in the patent to H. S. Hele-Shaw and T. E.Beacham, No. 1,983,884, granted December 1l, 1934, for Hydraulic ControlGear, in which the object is to apply a constant force to the fluidsystem at the transmitting end and to receive a corresponding constantforce at the receiving end. Another such system is shown in the patentto Alfred N. Lawrence, No. 2,197,554, granted April 16, 1940, for LiquidControl Gea-r, in which the object consists in applying a continuouslyincreasing load at the operated and receiving ends. in either of theaforementioned cases the operating and operated members will retain anyposition into which they may be moved without any tendency on their partto return to a centralized position.

In this type of transmission system a problem arises due to the factthat the fluid in the system changes its temperature causing contractionand expansion of the iiuid with consequent relative displacement of theoperating and operated members so that synchronism between these membersis lost unless synchronization is effected. Such loss of synchronismoccurs also when there is leakage of the fluid in the system. Thereforeit has been customary in transmission systems of the type described toprovide for synchronization at one end of the transmitter stroke atwhich time the connecting duct between the transmitting and receivingstations was connected to a fluid reservoir to permit interchange offluid so that the operating and operated members were again brought intosynchronism.

In the method of synchronization described above it was necessary tomove both the operating and operated members to their extreme positionsbefore synchronization could be effected. This was found to beundersirable in cases where the operated member had to remain in oneposition for a long period of time. Thus for instance in the case ofengine test stands where the operated member controlled the setting ofan engine throttle where the engine ran for several hundred hours, itWas undesirable to disconnect the engine from the operated member inorder to eiiect synchronization during the run. Therefore synchronismcould not be ef- 2 fected throughout the long period of the test run. Itis therefore one of the principal objects of this invention to provide asystem wherein synchronization may be effected at any time Withoutdisturbing the position of the operated member. i

Further objects. and advantages of this 'invention will become apparentin the following detailed description thereof.

In the accompanying drawings,

Fig. 1 is an assembly View with parts sectioned vertically of a liquidtransmission system embodying this invention.

Fig. 2 is an enlarged detail of a part disclosed in Fig. 1 with aportion thereof sectioned vertically.

Fig. 3 is a view of a locking means employed in the Fig. l form of theinvention.

Referring to the drawings, it Will be seen that the invention comprisesthree main parts, namely, a transmitting station T, a receiving stationR, and a force transferring connection or duct C, Duct C is iilled withuid in a column which extends from a transmitter piston I I to areceiver piston II. For applying force to the liquid column for thepurpose of transmitting force, there may be provided within thetransmitter T a cylinder I0 within which operates the piston Il. Thecylinder is connected at one end to lthe duct C' through passage I2within the transmitter casing I6. For operating the piston in adirection to transmit force to the liquid column lthere may be provideda transmitting element in the form of a lever I 4 pivoted within thecasing IS on a pivot H and having an operating handle I5 and the leveror crank arms I8 and ISA. The pivot I1 is supported at its ends in thecasing in suitable bearings. The crank, arm portion I8 is pivotallyconnected at I9 to the upper end of a piston rod 2t pivotally connectedto the piston at 2l. As the handle is moved in the direction of thearrow, the piston is lowered to cause the column of liquid to movethrough the duct C. The force which is applied to the piston isdetermined by one or more loading springs 22,. seated at one end againstthe bracket 23, fixed upon the sleeve 24, pivoted at 25. The other endof the loading spring bears against the bracket 2S iixed to a rod 28,which operates within the sleeve member 2li. The spring is undercompression and applies the loading force `to the lever arm IBA by wayof the pivotal connection 29 between the upper end of rod 28 and theoperating lever I4. The distance between the center of pivot I1 and thecenter of pivot 29 forms the crank arm I 8 through which the force isapplied. The positions of the spring and its connections are such thatthe spring acts through a small lever arm to apply a relatively lightloading force to crank arm I8 and the piston II when the piston is inits uppermost position, but as the handle I is actuated in the directionof the arrow it will be seen that the spring acts through an increasinglever arm. At the same time, however, the spring is extended, so thatwhile it acts through a larger lever arm it applies a decreasing forceto said arm as the latter increases. The design of the various parts maybe made such that the rate of decrease of the compressive force of thespring is equal to, greater than, or slower than the rate of increase ofthe lever arm as handle I5 is actuated in the direction of the arrow,depending upon the purpose to which the device is to be put, that is,Whether the product of these two factors is to be substantially constantto Vyield a substantially constant loading force, or

whether said product is to yield a continuously increasing or decreasingloading force.

The operation of handle I5 at the transmitting station just described tomove piston Il inwardly in its cylinder will cause piston II at thereceiving end to be moved outwardly in its cylinder and cause a pistonrod connected tc said piston, to actuate a lever I4 pivoted at I1. rlhepiston rod 20 is pivotally connected to one end of lever I4 at I9' andsaid lever I4' is pivotally connected at its other end at 29' to atwo-part extensible member 24-28 pivoted at its other end at 25 in thecasing I6', the said two-part element 24-28' being similar to theelement 24-28, at the transmitting end. The two parts similarly holdbetween brackets 23 and 26 one or more compression springs 22' similarto spring 22. The distances between pivot I1 and pivot I9 and between I1and V29 are the same as between pivot I1 and pivots I9 and 28. That is,it will be seen that the relationship of parts at the transmitter andthe receiver are the same but in inverse order and therefore a forcetransmitted by movement of piston II will produce an equal movement ofpiston I I. Y

' As stated in the introduction hereto, if there is leakage of fluidbetween piston l-I and piston II or if there is expansion or contractionof the fluid in said system during operation, then it will be apparentthat synchronism will be lost between the operating member I5 and theoperated member l5 unless synchronization can be effected. I-Ieretoforesuch synchronization was effected in the following manner: Thetransmitting handle or operating member I5 was operated in a clockwisedirection (in the drawing) until a projection 40 carried by a hub 4i onthe member I5 surrounding the pivot I1 struck a bell crank 42 Vto rockthe same around its pivot 43 and cause it to Vdepress a rod 44 extendingthrough a passage 45 in the casing I6, said passage communicating Vwitha passage 45 leading to the cylinder Ill.

Communication between passage 45 and passage 46 is normally closed by avalve 41, but when rod v44 is depressed said valve 41 is opened andcomthe bottom of its cylinder IU before piston I I has reached the topof its cylinder, then continued movement of piston VII upwardly aftervalve 41 4 has opened will allow uid from casing I6 to flow intocylinder I@ and ll it with uid. If by loss of synchronism piston II hasnot reached the bottom of cylinder I0' by the time piston II has reachedits upper limit and opened valve 41, then the springs 22' will movepiston Il downwardly to the bottom of cylinder ID to cause iiuid to passfrom the duct C through passages 45 and 45 into the casing I6. In eitherof the above cases synchronism is again eifected because before valve 41closes again piston II" will be at its lower-most position while pistonII is at its upper-most position, these positions constitutingsynchronism.

As stated in the introduction hereto, the hereinabove described methodof synchronization meant that the rocker arms I4 and I4 had to be movedto their extreme positions in order to effect synchronization, and sinceoperating member I5 and 'operated member I5 were heretofore both fixedto their respective pivots I1 and I1', this meant that whatever wasconnected to the operated member I5 had to be either disconnected ormoved with the member I5' to its extreme position. In cases such as testruns on engines where theoperated member I5-controls a given setting ofa throttle continuously for several hundred hours, it was foundinadvisable to disconnect the actuated member I5 during the test run,which meant that synchronization could not be effected throughout theperiod of said run.

By the following arrangement synchronization can be effected withoutdisturbing the position of the operated member I5. For this purposeoperating member I5 is fixed to its shaft I1 and operated member I5 isfixed to its shaft I1'. Rocker I4 is xedly attached to its pivot orshaft I1, but rocker I4 is releasably attached to its pivot or shaft I1.The connection between rocker I4 and shaft I1 is by way of a pin 5i!(Fig. 2) which seats in a detent or groove 5I in the pivot I1 and isnormally held'therein bythe fluid pressure in the transmission systein,said pressurel being transmitted to pin 5B by means of a duct 53 whichcommunicates at one end with the iiuid in cylinder I and at its otherend terminates in a cylinder 54 within which operates a piston 55 whichforms a head on pin 55. While the fluid pressure in the system ismaintained, as it always is until synchronization is effected, thepressure within the system is sufficient to keep pin 5I) within thedetent 5I so that the rocker Y arm I4' moves integrally with its pivotI1.

However when synchronization is to be effected the following means areemployed for releasing pin 56 from engagement with pivot I1 so thatrocker I4 can move independently of the pivot and thus not disturb theactuated member I5 which is fixed to pivot I1. For this purpose there isprovided in cooperation with shaft I1' a lock consisting of two members50 pivoted at one end on the casing at 62 and pivotally connected attheir other ends to a toggle joint 6i operated by a rod B3 which may bepart of the armature of a solenoid 64. The circuit through solenoidrdmay include a source of E. M. F. 65 and a switch comprising springmembers V65 mounted on operating member I5 and engaging a spring pressplunger 61 normally pressed by spring 58 Yto its upward position, inwhich position the contacts S5 engage an insulated member 59. Whensynchronization is tobe effected the operator presses down upon button10 at the upper end of plunger 61 to bring an electric conductingportion 1I into engagement with the spring fingers 66 to close 5 thecircuit through solenoid 64 and raise rod 63 to cause toggle joint 6I tobe raised so that shaft I'I is firmly locked against movement betweenlocking members Sil. The operator now moves handle I5 in a clockwisedirection (in the drawing), and since the shaft Ii' is held, piston Iicannot follow and suction is created in duct C. This causes a sharp dropin pressure in the transmission system which drops the pressure on thehead 55 in cylinder 54 and permits spring Bil to This occurs move thepin 5t out of its detent 5 i. immediately upon the first movement ofhandle I5 in the clockwise direction. Rocker Iii is now free to move onshaft II and as handle IE is moved to its extreme position with piston II in its extreme raised position to open valve 47, rocker arm I4 isrotating around the shaft I7' and piston II is descending.Synchronization is effected in the manner hereinbefore described, butactuated member I5' has not been disturbed. After synchronization hasbeen effected handle I5 is moved back in a counter-clockwise directionto cause the rockers I 4 and I4' to rotate until pin 50 snaps back intodetent 5I because pressure in the `system has been re-established assoon as handle I5 begins to move in the counter-clockwise direction.When pin 50 has snapped into its detent 5I the parts are in synchronizedposition without the actuated member having been disturbed.

`IIaving described my invention, what I claim and desire to secure byLetters Patent is:

1. A iiuid pressure transmission system comprising a transmittingstation, a receiving station, and a duct connecting said stations, eachstation having a casing, a cylinder communicating with said duct, and apiston in each cylinder, an operating member at the transmittingstation, an operated member at the receiving station, means connectingsaid members to the respective pistons, said means including a shaftrotatably mounted in each casing, said members being fixed to therespective shaft, a rocker xed to the shaft in the transmitter casing, a

rocker connected to the shaft in the receiver casing, each rocker beingconnected atone end `to the respective piston, spring means connected tothe other end of each rocker for applying force to the pistons, meansfor synchronizing the `pistons and the rockers, said last-named meansincluding a iiuid reservoir in the transmitter casing, there being apassage from the transmitter cylinder to said reservoir, means fornormally closing said passage, means for opening said passage when thetransmitter piston is at one end of` its stroke, means for releasing theconnection between the rocker and the receiver shaft when thetransmitter piston begins to move to synchronizing position, normallyineffective means for locking the shaft of the receiver againstrotation, and means for rendering said locking means effective prior tomoving the transmitter piston toward synchronizing position.

2. A fluid pressure transmission system asspecined in claim 1,characterized by normally ineffective means for locking the shaft of thereceiver against rotation. and means for rendering said locking meanseiective prior to moving the transmitter piston toward synchronizingposition, said means for releasing the connection between the rocker andthe receiver shaft being rendered eiective after the locking means isrendered efective.

3. A fiuid pressure transmission system as specii'ied :in claim 1,characterized by normally ineffective means for locking the shaft lofthe receiver against rotation, and means for rendering said lociringmeans effective prior to moving the transmitter piston towardsynchronizing position, said means for releasing the conneetion betweenthe rocker and the receiver shaft being rendered effective after thelocking means is rendered effective, said releasable connectioncomprising a pin slidable in said rocker, said shaft having a detent inwhich said pin engages.

4. A fluid pressure transmission system as specified in claim 1,characterized by normally ineffective means for locking the shaft of thereceiver against rotation, and means for rendering said locking meanseffective prior to moving the transmitter piston toward synchronizingposition, said means for releasing the connection between the rocker andthe receiver shaft being rendered eiective after the locking means isrendered eiiective, said releasable connection comprising a pin slidablein said rocker, said shaft having a detent in which said pin engages, acylinder, a piston operating in said last-named cylinder, said pistonbeing connected to said pin, and a duct connected at one end to thefluid pressure system between the transmitter and receiver pistons andconnected at its other end to said last-named cylinder.

5. A fluid pressure transmission system as speciiied in claim 1,characterized by normally ineffective means for locking the shaft of thereceiver against rotation, and means for rendering said locking meanseffective prior to moving the transmitter piston toward synchronizingposition, said means for releasing the connection between the rocker andthe receiver shaft being rendered effective after the locking means isrendered effective, said releasable connection comprising a pin slidablein said rocker, said shaft having a detent in which said pin engages, acylinder, a piston operating in said lastnamed cylinder, said pistonbeing connected to said pin, a duct connected at one end to the fluidpressure system between the transmitter and receiver pistons andconnected at its other end to said last-named cylinder, and a spring insaid last-named cylinder for moving said pin out of engagement with thereceiver shaft when the spring pressure exceeds the pressure in saidfluid pressure transmission system.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,339,728 Temple Jan. 18, 1944 2,416,054 Hebel Feb. 18, 19472,430,930 Hebel Nov. 18, 1947

